Torque meter



March 5, 1957 L. HoRNBosTEL. 2,783,645

TORQUE METER Filed May 8, 1955 2 4sheets-sheet 1 March 5, 1957 L HoRNBosTl-:L

TORQUE METER 2 Sheets-Sheet 2 Filed May 8, 1953 United States Patent() TORQUE NIETER Lloyd Hornbostel, Beloit, Wis., assignor to Beloit Iron Works, Beloit, Wis., a corporation of Wisconsin Application May 8, 1953, Serial No. 353,869

2 Claims. (Cl. 73-136) This invention relates to the measurement of power and torque transmitted through a mechanical drive system, and more particularly, to the measurement of torque transmitted through a gear train.

If an electric drive mechanism is employed, it is a relatively simple matter to determine the powerrequired to operate a piece of machinery since it is necessary only to measure the current and voltage applied tothe motor for operating this machinery. In the case of a mechanical drive such as that which is employed in the operation of paper machines, however, there is no simple means for continuously determining the power being transmitted. As will be appreciated, it is of particular importance to be able to ascertain the power transmitted at various points in the rather elaborate gear trains employed in the operation of heavy machinery such as paper machines. t

This is particularly true in the case of the differential drive in paper machines; but the necessity for determining the power transmitted in gear trains is equally great in the case of various other gear units.

In the case of a pair of coacting gears having parallel axes and having teeth on the periphery of each which are in parallel alignment with the axes, the force transmitted from one gear to therother is essentially the mechanical rotary or turning force known as torque The essential force component is the torque component in suchfcase and there is no force component axially aligned with one of said gears. On the other hand, in the case of almost -all other types of gear systems such las helical, bevel, spiral and hypoid gears both torque and axially-aligned forces are transmitted, so thatthe driving gear imparts ponents thus have-a definite relationship which may be determined in the case` of any particular type of force transmitting device. The instant invention involvesapparatus for employing these facts in the measurement of power and/or torque transmitted.

It is, therefore, an important object of the instant invention to provide an improved apparatus'for the measurement of power and/or torque in mechanical drivesystems.

Another object of the instant invention is to provide an improved drive mechanism comprising a first member and a second member each mounted for rotation, said lirst member being urged toward one axial position but movable axially away from said one position, and a torque-transmitting drive connection between said members applying an axial force to said first member tendingl to move said first member axially away froms'aidr one position, said axial force being a predetermined function (Sil ICC

of the torque being transmitted between said members.

A further object of the instant invention is to provide an improved apparatus for measuring the torque transmitted to a shaft having a helical gear drive involving torque and axially aligned force transmission in simultaneous predetermined relation, that comprises means axially floating the Arotating shaft to permit axial movement thereof in response to the axially aligned force transmitted and means; subjecting said shaft to a controlled but variable force opposite to said axially aligned transmitted force to the extentA necessary to maintain the shaft in a given axial location.

Other objects, featuresv and advantages will become apparent to those skilled in the art from the following detailed disclosure yof preferred embodiments of the instant invention, andthe drawings appended hereto and made a part hereof.

Onthe drawings:

Figure 1 is a fragmentary Vsectional elevational View of a drive mechanism embodying the instant invention;

Figure 2 is a sectional elevational view of another embodiment of theinstant invention; and

Figure 3 is a `sectional elevational view of :a modified element ladapted for use inthe embodiment shown in' Figure 2.

' As shown on the drawings:

The reference numeral 10 indicates generally a drive mechanism embodying the instant invention, which comprises a lirstmember or gear 11 .and a second member or gear 12 (sh-own partially only), each being mounted for rotation. In the instant embodiment (-Figurel) the gear 12 is mounted on a drive shaft (not shown), and the gears 11 and 12 are helical'gears thereby having a torque-transmitting -drive -connection between the gears 11 and 1|2-which applies 1an axial force to the. gear 11 tending to move the gear 11 axially away from its present position.` As was explained previously, the specific relationship between the torque `transmitted and the axial force appliedin a given gear system or other torquetransmitting device may be `readily calculated from the design and arrangement of the drive mechanism.

.In the embodiment of Figure l, the driven gear 11 is suitably mounted on a shaft 13 by means of keyways (such as at 13a) which are fitted with internal keys in the'hub portion 11a of the gear 11, so that the gear 11 is -secured to the shaft 13 for rotation therewith and axial movement therewith.

A sleeve or Aspacer 14 is `suitably mounted on a slightly reduced porti-on 13b of the shaft 13 and the sleeve 14 secures the driven` gear 11 in position on the shaft 13 by engaging the hub portion 11a at one end. 'At the opposite end of the sleeve 14 a suitable straight roller bearing assembly 15 is positioned.` The bearing assembly 15 comprises an inner bearing ring 15a mounted on the shaft 13, :an outer bearing 'ring 15b `and rollers 15C therebetween. This is a stra-ight'roller bearing assembly which permits limited axialmovement of the shaft 13 rotatably supported thereby.` The bearing lassembly 15 is suitably m'ounted-in a bearing housing 16, which has :an`

inner sleeve 16a against which the outer bearing ring 15bis retained by means of a ring member 17 and threaded bolts 18 -threadedly engaging the sleeve 16a and clamping the ring 17 against the ing assembly 15.

A thrust bearing assembly 19 is mounted within the housing 16 to cooperate with an additionally reduced extremity 13e of the shaft 13 t0 prevent axial movement in the direction of the bearing housing 16 while permitting limited axial movement in the opposite direction. The

thrust bearing assembly 19n comprises an innerfrustoconical ring 19a mounted oni-the reduced shaft portion 13e,

a mating outer bearing ring 19b, and rollers 19C there- Yinner side of the bear-` :ressens between. The outer ring' 191i is securely held against a shoulder portion 16b. in, the4 inner housing sleeve 16a, so. as to prevent axial movement in the direction of the housing. Suitable oil conduits 20, provide means for ilowing oil through the' housing 1-6 and4 inner sleeve 16a and between :the'bearingassemblies 15 and` 19'to provide suitable lubrication. for the operation ofsuch bearing assemblies.

inthe operationof the instant drive mechanism 10, the gears: 11 and 12 are so designed and= operated that the axial. force or thrust impanted by the drive gear 12 to the driven gear. 11 is direc-ted away`r from the housing 16, since the thrust bearing assembly- 19-prevents axial movement in the direction of the housing 16- but permits axial movementin: the opposite direction.

As will be explained in detailg the-bearinghousing-21 atftheend. of vtheshaft 113 oppositei toY the end receivedby thebeaning housing 16 is so designedI that it operates tor urge the shaft 13 andi the driven gear-11 toward the housing 161er toward' anaxia'lposition approximately-asshown in Figure l wherein the -thrust bearing assemblyA 19 permits funther axial movement lin the direction of the housing 16. The arrangement within the bearing housing 21 thus tends to urge the shaftl 13A andi the driven gear 11' toward one axial posi-tion; but permits axial movement of the shaft 13 away from this axial positionin-the directiontof the housing 21.

Referring now to the detailsof( the housing 21, it will` be seen that the housing is equipped with an innery ring 21a which retains a straight rolle-rl bearing assembly 22 comprising an inner-ring.- 22amounted` on` a reduced portion 13d. of. theshaft 13, anv outer ring 22b engagingthe sleevev 21a, and rollers 22e therebetween.` The bearing assembly 22 like the bearing: assembly 15- is a straightV roller bearing assemblyl which-permits limited axial movement.

Itwill also. be notedtha-t the inner ring 22a engagesa spacer or sleeve 23 (functioning-in the same manneras the spacer 1i4 at the oppositeend off' the shaft 13) which spacer 23 surrounds the reduced portion ldof the shaft 13 and engagessat one'endn thereofthe inner bearing ring 22a andi at the opposite end thereof the hubportion 24a of a spur gear 24, whichzis mountedllike the gear 11 in keyways such as. the keyway 13e and retained inA such keyways 13e by the spacer 23?. The spur gear 24 isV drive mechanism, so :that the problem ofl calculating the torque transmitted4 to, the shaft 13` may-bei simplifiedl The inner housing. sleeve.21a. hastan. outwardly turned flange portion 2lb to whichI is. secured a housing 25l by means of ange bolts. 26. As will be noted, the inwardmost portion 25ar of the housing 2S clampinglyengages the outer bearing ring 2211. with the inner housing sleeveA 21a to retain theL samev in positionv (axial movement through the bearingl assembly 22 being accomplished by sliding of Vthe rollers 22c on theinner periphery of the outer` ring 22b). Thel housing 25v provides a closed generally cylindricalv chamber extending from. the bearing assembly 22r tothecap or-head'portionZSb' of! thehousing- 25 and separated into a fronti chamber.- A and a: back chamber B by means of a piston member 27j. As will be seen, the piston member 27 is an annular member mounted on the extreme reduced endzportion 13f of the Shaft 1.3; and the end portion 13`f'and the annular member 27 cooperate to define a pistonl axially receivedwithin` lthe cylinder defined by 4the housing A25 and; slidable therein-inA accordance with the, axiall movement ofthe shaft 13. Fluid under pressure' in. the-outer'clramber tends.

4. to urge the piston and the shaft 13 axially in the direction of. the opposite bearing housing 16;

In the operation of the instant device, a suitable uid under pressure, such as lubricating oil in the embodiment here shown is fed through a pressure line 28 then through a control (or choke) valve 29 which functions as a letdown valve for the fluid under pressure, and then through an inlet line 30 which communicates with the chamber A through a suitable aperture 25e in the housing 25. As shown inthe particular arrangement o'f Figure l, theuid. then passes through an axially aligned port 31; inthe shaft 13 and then through a plurality of radially aligned restricted ports `32'. which provide communication between the axial port 31 and the inner chamber B. From the inner chamber B excess oil` may ow outwardly through the oil port 33 passing through the members 25a, 21a and 21 (for returning the oil to the lubricating system).

During, the operation of the instant device 10, however, a cap screw 34i`s positionedinthe housing 25 so that the inner face 34a of the screw 3'4 is closely adjacent the outer end' or face of the shaft 13, so as to substantially close olf the port 31. During operation of the dii've mechanism I0,V the coaction between, the gears 11` and 12 causes the shaft 13 to be urged flush against the screw face 34a, thereby closing off the port 31. Alsoduring this operation,v the oil under pressure flows through the choke valve 29" and; into the chamber A. As soon as the oilipressure-in'the chamber A is sufficiently great to urge the' shaft: 13 toward the bearing housing 16, a small amount of oil? may ow between the shaft end' and the screw'face' 34a and' intothe port 3l', thus-relieving the pressure. By this operation, the pressure in chamber A is continuously- :that pressure which is suflicient to bi'as ythe shaft* 13'i1rwhat amounts to a neutral position. The neutral' posi-tion is a position wherein the shaft is substantiallyusli against' thecap screw face 34a, thereby permitting only1 slightV leakage to compensate for the tendency for pressure to buildup in the chamber A, as a result of oil1 passing through the choke valve 29` from a pressure source (not shown) having substantially greater pressure thanY thatY contemplated for use inchamber A. FPhis llowV of oil is relatively slow, so that thegauge 35' whichcommunicates with -the inlet line. 30hy the gauge line 36 may register substantially the fluid' pressure in the chamber A. The area against which` the fluidpresf sure is` appliedin chamberA may, ofcourse, be readily calculated from the dimensions of the end' of the shaft 1'3- andv the outer-face ofthe annularV member 2'),4 so that the total force exerted axially againsty the shaft 13 may becalculated. WhenY the shaft 13 is biased or; urged into neutral position, asdescribed, the total'forcev exerted by the tluid pressure is equal tothe total force exerted' by the axial forcecomponent generated" by the coactionl between the gears 11' and l-Z This axial forceV component isV a' predeterminedE function of thetorque generated or' transmitted' between thel gears-11 andJ 12, and the torque-trans` mittedt may thusbecalculated solely on 'the basis'ofthe reading-ofthe lpressure gauge 35i Asu will be noted, the cap screw 34 threadedly engages thel housing heador endl 25a, so thatl tmay be adjusted axially toA effect an adjustment ofl the neutral axial position for operation. A lock nut 37 maybe-usedv to hold the cap screw 34 in fixed position once adjustment is made; andla cap 381 is-` removably. attached to the-housing 25'so1as.` topermit' access to the cap screw when adjust'- mentI is necessary;

As will be appreciated, other indicator means including: recording4 means, may be-used in place of thegauge 35ito-indicate-the fluid pressure, toindi'cate-the continuousachangesin the fluidpressure; or even'toindicate' the torque transmitted assuoli (merelyv by changing thegradationsor-indicia `in the gauge)`1.

As previously explained; the fiuidf pressure urges' the shaft in: onev axial direction' toward" agiven neutral` axial# position, which isriust slightly away from theicap' screwA face' 34a; ,and thefsha'ft is also being: gedl away from this axial Yposition (and tlushfagainstthecap screw face 34a) by the axial force component generated during torque transmission. The uid pressure generated force is thus a force which is resilient vin nature,\although it continuously urges the shaft 13 in one direction. `The resilience of such uid pressure may, of course, be greatly increased by the use.of a gas (such as compressed air) instead of the oil to obtain the `desired lluid pressure. Also, spring means may be used, as will be described in connection with Figure 3, to provide resilient means for urging the shaft 13 in the axial directionfindic'ated. Also, the piston and cylinder arrangement lmay be reversed, if such is desired so that the cylinder, forexample, might be aixed to the end of the shaft 13 and a non-movable piston might cooperate therewith, skilled in the art will readily appreciate. f l

In general, the torque transmitting drive connection between the two principal rotary membei's- (as here shown the gears 11 and 12) must involve an axial force component as well as the force component involved in the' torque transmission per se.A The torque may fthus'be transmitted from the driving member 12 toythe driven member 11 along the line of the surface-engagement between the teeth mounted on each of such members 11 and 12. In a helical gear arrangement, this `line is non-parallel to the axis of either of the gears 11 and 12 (the axes of the gears 11 and 12l being parallel), but this line lies in a plane (at the point'of contact between the teeth) which plane is substantially ,parallel to the axes of both shafts. The force components in vthis plane may be resolved into a line of force thatfis perpendicular to a plane drawn through the axes of the two gears (which line of force is tangential to the'driven gear 11 yand provides the torque component) and a .lineof force which is parallel to the axes of the two gears, which is the axially aligned force component.

It will be appreciated that an axial force component is also generated in other types of gear systems such as the spiral, bevel or hypoid gears. in which cases the axes of the gears are not necessarily parallel nor are they necessarily intersecting axes. Each of these various gear systems has a specific axial arrangement between the gears as well as a specific tooth arrangement on the operating faces of the gears, as those skilled in the art know well; and in each case an axial force component is generated as well as the pure torque transmitting force component. Preferably in the operation of the instant invention the gears are not coaxial, so that relative limited axial movement of one of the gears may be easily provided for in accordance with the teachings of the instant invention; and one of the gears may be held against axial movement and the other may be mounted to permit limited axial movement.

It will thus be seen that in the instant invention, the

shaft 13 is rotated so as to permit axial floating to a limited extent and this axial floating accommodates axial movement of the shaft in response to the axially aligned force component transmitted thereto. The shaft is also subjected to a controlled but variable force (preferably fluid pressure) opposing the axially aligned transmitted force to the extent necessary to maintain the shaft in a given axial location. The shaft is thus maintained in the neutral axial position by counterbalancing the constantly biasing force of the fluid pressure against the constantly biasing force resulting from the axially aligned transmitted power.

Referring now to Figure 2, it will be seen that the device 50 shown therein comprises a shaft 51 which is mounted for limited axial movement on a pair of straight roller bearings 52 and 53 and carries a pair of co-rotatable gears 54 and 55. The straight roller bearing 53 is housed in a bearing housing 56 which also contains a thrust bearing assembly 57 which prevents axial movement of the shaft 51 in the direction of the housing-50 as those' 6 (i.` e., prevents vaxial 'movement' past the thrust bearing assembly 57);but permits'axial movement of the'y shaft 51 inthe opposite direction. A vhelical drive gearf58 is meshedV with the helical Vdriven gear S4 to vprovide a torquetransmitting drive connection between the gears 54 and 58,in vthe manner `hereinbefore indicated. Thisl torque transmission results in an axial force component, in this case in the direction toward the lef-t and away from Y the bearing housing 50, in the manner hereinbefore'indi-A cated. A`rotary, universal type joint 59 is connected to the 'end of the shaftY 51 opposite the bearing housing 50 foraxial movement therewith and a non-rotating connecting rod 60 is affixed to the non-rotating portion of the joint 59. The connecting rod 60 is pivotally connected to one endof a lever arm 61` which is mountedl on the fixed fulcrum 62 near the pivot connection 63 with theY connecting rod 60 and hasa pivot 'connection 64:at the opposite end thereof. The pivot connect-ion 64 is made'with a connecting shaft 65 for a piston and cylinder assembly 66. In the piston and cylinder assembly 66, the cylinder 67 is fixedly mounted on a bracket 68 and the piston 69 connected to the piston rod 65 moves axially within the cylinder 67. The piston 69 and the cylinder 67 cooperate -to denne a fluid pressure chamber C on one side of the piston 69, and fluid under pressure from a source (not shown) islfedthrough a high pressure, line 70, a choke valve 71 and an` inlet line 721into the charn-V ber C. YA pressure gauge line 73 also communicates with the chamber C and is terminated by a pressure gauge 74, so as] to register thetluidV pressure inthe chamber C. The fluid vpressure in the chamber C exerts force against the piston so as to urge Ithe piston axially in the opposite dir'ectionto tha-t direction whichl the axial transmitted force urges the piston 69. lIn other words, the axial force transmitted urges the shaft 51 to the left and by virtue of -the'leverlarm 61 urges the piston 69 to the right,` as

shown in Figure 2. The fluid pressure in the chamber lC.

urges the piston to the left. The neutral position for the piston is defined by means of a bleed-oil` aperture 75 in the wall of the ycylinder 67. The bleed-off aperture is located adjacent the working face 69a of the piston 69, so that the accumulation of fluid pressure above and beyond that necessary to counterbalance the axial thrust transmitted to the shaft 51 will result in movement of the piston 69 a very slight distance to the left, so as to uncover the port 75. Excess pressure may thus be bled olf through the port 75, until the pressure in the chamber C is just sufficient to balance the axial thrust on the shaft 51 and the piston 69 then moves the very slight distance to the right necessary to close the port 75. Actually, the pressure in the chamber C will drop just below that necessary to balance the piston and the piston, in moving the incremental distance necessary to close the port 75, will complete the necessary pressure buildup in the chamber C.

As another embodiment of the instant invention, the lever arm 61 might be equipped with a spring device, such as that shown in Figure 3, wherein the modified lever arm comparable to the lever arm 61 is indicated by the reference numeral 61', and the modified pivot is indicated by the reference numeral 64. ln the embodiment of Figure 3, a connecting rod 76 is pivotally connected to the lever arm 61 by means of the pivot 64 for axial movement in response to swinging movement of the lever arm 61'. The connecting rod 76 is received by a spring housing 77 having therein a spring 78 mounted to resist compression. The spring 78 is held between the housing end 77a (suitably apertured -to receive the connecting rod 76) and a head member 79 secured to the free end of the connecting rod 76, so as to clamp the springl 7 nesting rod 76 .to the left, as shown @in Figure 3. The amount :of-,compression or compressive force-exertedby thesspring 78 .intorder-to maintain a neutral latrial ,position (for the shaft 51 as .wellas the connecting rod t76 may be -measured by -the gauge v80, .in the usual :mannen so ,as to-obtain .a reading indicating :the ,totals foroetof the axially alignedfforcecomponent operatingon the -shafLSfL -From the .total Vof the axial force componentg-itjs a simple :mat-- ter to calculate the amount of torque (tand from the amount `of -torque it is ta simple :matter tto calculate the power .transmitted ybetween the ,gears 54 and "58 taking into consideration the speed of 1rotationt).k As shown-in Figures Zand 3, `it -is `desirable yto -employ .a `lever, arm 61 .or .61 that is so ttulcrumed that .only a very t-small amount .of movement offtheconnecting-rod -60 .is necessary .in -order -to accomplish a rather .substantial .amount of movement .by the piston `rod 65 .or the :spring eonnecting .rod .76, whichever the Vcase .may Ibe, .so r.that the readings of .the .gauges 74 ior :80 may lbe obtained -with additional accuracy, without :the necessity Yof Nery sulA stantial axial movement of the-shaft 51 .duringoperation Itwill be understood that modifications and variations may be `effected without departing from zthescope offthe novel `concepts-ofthe present invention.

I claim asmy invention:

l. A gear .drive comprising a shaft rotatably :mounted forlimited axial movement, a pair of helical Egears, :one of said gearsbeing co-rotatably'mounted-on-said shaftand the other drivingly engaging Isaid one ,-gear to transmit torque and axially aligned `orcestherebetween, a-pston connected to said shaft for vaxial ,movement therewith, -a cylinderreceiving said piston and dening therewith a fluid :pressure lchamberon -one side -of said piston, :fluid pressure .inlet Vand outlet means lfor 'said chamber, :Said

uid pressure outlet means being mounted in saidpiStOn i and .defining an outlet aperture on said one side of :said piston, said chamber having an aperture .axiallyaligned withcsaidtoutlettapetture, and gplug means in said chamher aperture gprgiectng .into A.said chamber presenting aa face portion vopposing ,-said v-.outlet-.aperture, said plug means being .adiustably movable axially tot said Apiston whereby said -face 1portionmay-limit-fluid pressure leakagethroughsaid outlet.=aperture.

2. .A .gear :drive :comprising.a.shaft rotatably mounted for ,-.limitedaxial movement, a pair of helical gears, -one of said gears tbeing .co-rotatably Amounted -on said :shaft and -the fother :drivingly engaging said .one -gear -to transmit torquezand a-xially .aligned forces therebetween, a piston connected to said shaft for .axial movement therewith, a cylinder .receiving saicbpiston anddening therewith ra ruid l,pressure vchamber on -one side 1 of said piston, iluid pressure. ,inlet vand -outlet :means -for said chamber, said fluid ,pressure .outlet Ameans `,being .mounted in said piston and defining an Voutlet aperture on said one iside of isaid `piston, vsaid chamber .having .an aperture axially aligned .with said-.outlet aperture, and ,plug means -insaid chamber aperture iprojecting into `said chamber .presenting a face portion .opposing said -outlet aperture, said plugmeans being -adjustably movable axially-of said ;pis ton `.whereby said face -portion may .limit .uid pressure leakage .through said outlet.aperture,:andindicator means connected to saidchamberto indicate l.the -uid pressure therein.

References-.cned in the aie-ef this .patent temmen STATES PATENTS l',272,041 ."Herr July -9, 19.18 'l',298;63`0 Sehmiilt `Mar. 25, 1919 1,316,281 "Dlton Sept. 16K, .1919 22386367 I 4Taylor Oct. 9, .1945 231144363 Newcomb rIune 29, 1948 l2,517,038 'Sheliild Aug. 1, 1950 2;578,474 'Haworth Dec. 1, 1951 

